WO2017098848A1 - High entropy alloy member, method for producing alloy member, and product using alloy member - Google Patents

Abstract

The purpose of the present invention is to provide: a high entropy alloy (HEA) member which uses a high entropy alloy having high mechanical strength and high corrosion resistance, and has excellent uniformity of alloy composition and microstructure and excellent shape controllability; a method for producing the HEA member; and a product using the HEA member. The HEA member according to the present invention is an alloy member comprising an HEA, and is characterized by having a chemical composition containing elements Co, Cr, Fe, Ni, and Ti, each within the range of 5-35 atom%, and Mo within the range of more than 0 atom% but not more than 8 atom%, the balance being unavoidable impurities, and is characterized in that, in the alloy member, an intermetallic compound phase of needle-like crystal is dispersed and deposited in parent-phase crystal.

Description

High entropy alloy member, method for producing the alloy member, and product using the alloy member

The present invention relates to a technology of a high entropy alloy, and more particularly to a high entropy alloy member produced by a powder additive manufacturing method, a method for producing the alloy member, and a product using the alloy member.

In recent years, a high-entropy alloy (High Entropy Alloy) has been developed as an alloy with a new technical concept that is completely different from the technical concept of a conventional alloy (for example, an alloy obtained by adding a few minor component elements to one to three main component elements). Entropy Alloys (HEA) has been proposed. HEA is defined as an alloy composed of five or more kinds of main metal elements (each 5 to 35 atomic%), and is known to exhibit the following characteristics.

(A) Stabilization of the mixed state due to negative increase of the mixing entropy term in Gibbs free energy equation, (b) Diffusion delay due to complex fine structure, (c) High due to size difference of constituent atoms Increased hardness due to lattice distortion, reduced temperature dependence of mechanical properties, and (d) improved corrosion resistance due to combined effects (also called cocktail effect) due to coexistence of multiple elements.

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-173732) discloses a high-entropy multicomponent alloy obtained by casting or synthesizing a plurality of types of metal elements, the alloy containing 5 to 11 types of main metal elements, A high-entropy multicomponent alloy is disclosed in which the number of moles of one main metal element is 5% to 30% of the total number of moles of the alloy. Further, it is described that the main metal element is selected from a metal element group including aluminum, titanium, vanadium, chromium, iron, cobalt, nickel, copper, zirconium, molybdenum, palladium, and silver.

According to Patent Document 1, it is said that a high-entropy multicomponent alloy having higher hardness, higher heat resistance and higher corrosion resistance than conventional carbon steel and alloy carbon steel can be provided in a cast state.

JP 2002-173732 A

However, the present inventors conducted various studies on HEA, and as a result, HEA is prone to element segregation and texture spots during casting due to the complexity of the alloy composition, and it is difficult to obtain a homogeneous ingot. It was. Element segregation and texture spots in alloy members are problems to be solved because they lead to variations in characteristics depending on the part.

Further, HEA has high hardness and resistance to tempering softening, so that it is difficult to process, and it is difficult to produce a desired shape member by machining. This is a major obstacle to commercialization and commercialization of HEA members, and a problem to be solved.

On the other hand, as mentioned above, HEA has attractive features that cannot be obtained with conventional alloys. Therefore, HEA members with excellent alloy composition / microstructure homogeneity and shape controllability, and their manufacture There is a strong need for method development.

Accordingly, the object of the present invention is to use a high-entropy alloy (HEA) having high mechanical strength and high corrosion resistance to satisfy the above requirements, and is excellent in alloy composition / microstructure homogeneity and in shape controllability. An object of the present invention is to provide a HEA member, a manufacturing method thereof, and a product using the HEA member.

(I) One aspect of the present invention is an alloy member made of a high-entropy alloy,
Co (cobalt), Cr (chromium), Fe (iron), Ni (nickel), Ti (titanium) elements each in the range of 5 atomic percent to 35 atomic percent, and Mo (molybdenum) 0 atoms In a range of more than 8% and less than 8 atomic%, with the remainder consisting of inevitable impurities,
The alloy member provides a high entropy alloy member in which an intermetallic compound phase of needle-like crystals is dispersed and precipitated in a matrix crystal.

The present invention can add the following improvements and changes to the high entropy alloy member (I).
(I) The acicular crystals are dispersed and precipitated in a three-dimensional lattice shape.
(Ii) The chemical composition of the high-entropy alloy is such that the Co is 20 atomic% to 35 atomic%, the Cr is 10 atomic% to 25 atomic%, and the Fe is 10 atomic% to 25 atomic%. The Ni is contained in an amount of 15 atomic% to 30 atomic% and the Ti is contained in an amount of 5 atomic% to 15 atomic%.
(Iii) The chemical composition of the high-entropy alloy is such that the Co is 25 atomic% to 33 atomic%, the Cr is 15 atomic% to 23 atomic%, and the Fe is 15 atomic% to 23 atomic%. The Ni is contained in an amount of 17 to 28 atomic%, the Ti is contained in an amount of 5 to 10 atomic%, and the Mo is contained in an amount of 1 to 7 atomic%.
(Iv) The high-entropy alloy has a chemical composition of 27 atomic% to 33 atomic% of Co, 18 atomic% to 23 atomic% of Cr, and 18 atomic% to 23 atomic% of Fe. The Ni is contained in an amount of 17 atom% to 24 atom%, the Ti is contained in an amount of 5 atom% to 8 atom%, and the Mo is contained in an amount of 1 atom% to 3 atom%.
(V) The intermetallic compound phase includes a Ni ₃ Ti phase.
(Vi) Tensile strength is 1000 MPa or more and elongation at break is 3% or more.
(Vii) The parent phase crystal has a columnar crystal shape and includes a simple cubic crystal. Here, “the crystal structure includes a simple cubic crystal” means “the main crystal structure is a simple cubic crystal”.

(II) Another aspect of the present invention is a method for producing the high entropy alloy member described above,
A raw material mixing and melting step of mixing and melting the raw materials of the alloy to form a molten metal;
An atomizing step of forming alloy powder from the molten metal;
There is provided a manufacturing method of a high-entropy alloy member, comprising: a layered manufacturing step of forming an alloy layered body having a desired shape by a metal powder layered manufacturing method using the alloy powder.

The present invention can add the following improvements and changes to the above-described high entropy alloy member production method (II).
(Viii) The additive manufacturing process includes a powder bed forming process for forming a powder bed of the alloy powder,
A powder bed calcining step of heating the entire powder bed to form a pre-sintered powder bed;
The temporary sintered body is locally heated to form a micro molten pool of the alloy, and the micro molten pool is moved and sequentially solidified while scanning the local heating in the plane of the temporary sintered body. And a local melting / solidifying layer forming step of forming a solidified layer of the alloy.

(III) Still another embodiment of the present invention is a product using the above-mentioned high entropy alloy member,
Provided is a product using a high-entropy alloy member, wherein the product is an impeller of a fluid machine.

In the product (III) using the above-described high-entropy alloy member, the present invention can be improved or changed as follows.
(Ix) The product is a centrifugal compressor incorporating the impeller.

According to the present invention, a high-entropy alloy (HEA) having high mechanical strength and high corrosion resistance is used, an HEA member having excellent alloy composition / microstructure homogeneity and excellent shape controllability, and a manufacturing method thereof, and A product using the HEA member can be provided.

It is process drawing which shows an example of the manufacturing method of the high entropy alloy member which concerns on this invention. It is a cross-sectional schematic diagram which shows the structure of the powder additive manufacturing apparatus of an electron beam melting method, and the example of an additive manufacturing method. It is an electron microscope observation image which shows the example of the fine structure of the cross section of the alloy lamination-modeling body which consists of HEA which concerns on this invention. It is an electron microscope observation image which shows the example of the fine structure of the longitudinal section of the alloy lamination-modeling body which consists of HEA which concerns on this invention. It is an example of the product using the HEA member which concerns on this invention, and is a photograph which shows the impeller of a fluid machine. It is a cross-sectional schematic diagram which is another example of the product using the HEA member which concerns on this invention, and shows the centrifugal compressor incorporating the impeller of this invention. It is an electron microscope observation image which shows the example of the fine structure of the HEA member 1c.

(Basic idea of the present invention)
As described above, high-entropy alloys (HEA) have attractive characteristics (such as high hardness and temper softening resistance) that cannot be obtained with conventional alloys, but they are difficult to process and have the desired shape. There was a problem that it was difficult to produce a member. Further, as a result of various studies on HEA by the present inventors, it has been found that a HEA ingot having a conventional ordinary cast structure has high deformation resistance and poor ductility.

Therefore, the present inventors have conducted extensive research on alloy compositions and shape control methods in order to develop HEA members having excellent shape controllability and ductility without sacrificing the characteristics of HEA. As a result, it was found that an HEA member that solves the problem can be obtained by forming an alloy additive manufacturing body by a metal powder additive manufacturing method using powder of a Co-Cr-Fe-Ni-Ti-Mo alloy. . The present invention has been completed based on this finding.

Hereinafter, an embodiment of the present invention will be described along a manufacturing procedure of HEA members with reference to the drawings. However, the present invention is not limited to the embodiments described here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

[Method for manufacturing HEA members]
FIG. 1 is a process diagram showing an example of a method for producing a high-entropy alloy member according to the present invention. As shown in FIG. 1, the manufacturing method of this invention has a raw material mixing melt | dissolution process, an atomizing process, an additive manufacturing process, and an extraction process. Hereinafter, embodiments of the present invention will be described more specifically.

(Raw material mixing and dissolving process)
As shown in FIG. 1, first, a raw material mixing and dissolving step is performed in which raw materials are mixed and dissolved to form a molten metal 10 so as to have a desired HEA composition (Co—Cr—Fe—Ni—Ti—Mo). There are no particular limitations on the method of mixing and melting the raw materials, and conventional methods in the production of high strength and high corrosion resistance alloys can be used. For example, vacuum melting can be suitably used as a melting method. Further, it is preferable to refine the molten metal 10 together with a vacuum carbon deoxidation method or the like.

The HEA composition of the present invention includes 5 elements of Co, Cr, Fe, Ni, and Ti as main components in a range of 5 atomic% to 35 atomic%, respectively, and Mo as an auxiliary component is more than 0 atomic% and less than 8 atomic%. And the remainder consists of inevitable impurities.

More specifically, the Co component is preferably 20 atom% or more and 35 atom% or less, more preferably 25 atom% or more and 33 atom% or less, and further preferably 27 atom% or more and 33 atom% or less.

The Cr component is preferably 10 atomic percent to 25 atomic percent, more preferably 15 atomic percent to 23 atomic percent, and still more preferably 18 atomic percent to 23 atomic percent.

The Fe component is preferably 10 atomic percent to 25 atomic percent, more preferably 15 atomic percent to 23 atomic percent, and still more preferably 18 atomic percent to 23 atomic percent.

The Ni component is preferably 15 atomic% to 30 atomic%, more preferably 17 atomic% to 28 atomic%, and still more preferably 17 atomic% to 24 atomic%.

The Ti component is preferably 5 atom% or more and 15 atom% or less, more preferably 5 atom% or more and 10 atom% or less, and further preferably 5 atom% or more and 8 atom% or less.

The Mo component is preferably more than 0 atom% and less than 8 atom%, more preferably 1 atom% to 7 atom%, and still more preferably 1 atom% to 3 atom%.

When the above components are out of their preferred composition ranges, it is difficult to achieve desirable characteristics.

(Atomizing process)
Next, an atomizing process for forming the alloy powder 20 from the molten metal 10 is performed. There is no particular limitation on the atomizing method, and a conventional method can be used. For example, a gas atomization method or a centrifugal atomization method that can obtain high-purity, homogeneous composition, and spherical particles can be preferably used.

The average particle diameter of the alloy powder 20 is preferably 10 μm or more and 1 mm or less, and more preferably 20 μm or more and 500 μm or less, from the viewpoints of handling properties and filling properties. When the average particle size is less than 10 μm, the alloy powder 20 is likely to rise in the subsequent layered manufacturing process, which causes a decrease in the shape accuracy of the alloy layered body. On the other hand, when the average particle size exceeds 1 mm, it becomes a factor that the surface roughness of the alloy layered structure is increased or the melting of the alloy powder 20 becomes insufficient in the next layered manufacturing process.

(Laminated modeling process)
Next, an additive manufacturing process for forming an alloy additive manufacturing body 230 having a desired shape is performed by a metal powder additive manufacturing method using the alloy powder 20 prepared above. By applying a metal powder additive manufacturing method for forming a near net shape metal member by melting and solidification instead of sintering, a three-dimensional member having a complex shape with a hardness equal to or higher than that of a cast material can be produced. The additive manufacturing method is not particularly limited, and a conventional method can be used. For example, a metal powder additive manufacturing method using an electron beam melting (EBM) method or a selective laser melting (SLM) method can be suitably used.

The additive manufacturing process will be described using the EBM method as an example. FIG. 2 is a schematic cross-sectional view showing an example of a structure of an EBM method powder additive manufacturing apparatus and an additive manufacturing method. As shown in FIG. 2, the EBM powder additive manufacturing apparatus 100 is roughly divided into an electron beam control unit 110 and a powder control unit 120, and the whole is a vacuum chamber.

1) The stage 121 is lowered by one layer thickness (for example, about 30 to 800 μm) of the alloy laminate model 230 to be modeled. The alloy powder 20 is supplied from the powder hopper 123 onto the base plate 122 on the upper surface of the stage 121, and the alloy powder 20 is flattened by the rake arm 124 to form a powder bed 210 (layered powder) (powder bed forming step).

2) Thermoelectrons are emitted from the heated tungsten filament 111 (for example, 2500 ° C. or higher) and accelerated by the anode 112 (for example, about half the speed of light) to form an electron beam 113. The accelerated electron beam 113 is rounded by the astigmatism correction device 114 and focused on the powder bed 210 by the focus coil 115.

3) A relatively weak (loose) focused beam is scanned by the deflection coil 116 to preheat the entire powder bed 210 to form a temporary sintered body of the powder bed. In the EBM method, it is preferable to perform a step of forming a pre-sintered powder bed (powder bed calcining step) before locally melting and solidifying the powder bed. This is to prevent scattering of the powder bed due to charging of the alloy powder by irradiation with a focused beam for local melting. In addition, there is an additional effect that the deformation of the alloy laminate model 230 is suppressed by the heating in this step.

The calcining temperature of the powder bed 210 is preferably 900 ° C. or higher and 1000 ° C. or lower. When the calcining temperature is less than 900 ° C., the sintering of the alloy powder hardly proceeds, and it becomes difficult to form a calcined body. On the other hand, when the calcining temperature exceeds 1000 ° C., the sintering of the alloy powder proceeds so much that it is difficult to take out the alloy laminate model 230 (separation between the alloy laminate model 230 and the provisional sintered product).

4) Based on the 2D slice data converted from the 3D-CAD data of the alloy layered object 230 to be shaped, the presintered body of the powder bed is irradiated with a strong focused beam for local melting and alloyed In addition, a 2D slice-shaped solidified layer 220 is formed by scanning the focused beam and moving and sequentially solidifying the fine molten pool (local melting / solidified layer forming step).

5) Repeat steps 1) to 4) to form an alloy laminate model 230 having a desired shape.

(Removal process)
Since the alloy layered product 230 formed in the above process is buried in the temporary sintered body, an extraction step of taking out the alloy layered model 230 is performed next. There is no particular limitation on the method for taking out the alloy laminate model 230 (the separation method between the alloy laminate model 230 and the temporary sintered body, the separation method between the alloy laminate model 230 and the base plate 122), and the conventional method can be used. . For example, sand blasting using the alloy powder 20 can be preferably used. Sandblasting using the alloy powder 20 has an advantage that it can be reused as the alloy powder 20 by crushing together with the alloy powder 20 sprayed with the removed pre-sintered body.

[HEA material]
After the extraction step, a sample for observing the microstructure was collected from the alloy laminate model 230, and the microstructure of the sample was observed using an optical microscope and an electron microscope. As a result, the parent phase of the alloy laminate model 230 has a structure in which fine columnar crystals (average particle size of 100 μm or less) are forested along the lamination direction of the alloy laminate model 230 (so-called rapid solidification structure). It was. As a result of further observation, it was observed that in the alloy laminate model 230, acicular crystals of an intermetallic compound phase were dispersed and precipitated in a lattice pattern in the parent phase crystal.

FIG. 3A is an electron microscope observation image showing an example of a microstructure of a cross section (a surface perpendicular to the stacking direction and a surface in which the stacking direction is a normal line) of an alloy laminate model formed of HEA according to the present invention. FIG. 3B is an electron microscope observation image showing an example of a microstructure of a longitudinal section (a surface along the stacking direction, a surface having a normal line perpendicular to the stacking direction) of the alloy laminate shaped body made of HEA according to the present invention.

As shown in FIG. 3A and FIG. 3B, since the acicular crystals are dispersed and precipitated in a lattice shape in both the cross section and the longitudinal section of the alloy laminate model 230, the acicular crystals are three-dimensional. It was thought that it was dispersed and precipitated in a lattice form.

[Products using HEA components]
FIG. 4 is a photograph showing an impeller of a fluid machine as an example of a product using the HEA member according to the present invention. Since the HEA product of the present invention is manufactured by the metal powder additive manufacturing method, even a complicated shape as shown in FIG. 4 can be easily modeled. Further, since the impeller using the HEA member of the present invention has both high mechanical properties and high corrosion resistance, it can exhibit excellent durability even under severe stress / corrosion environments.

FIG. 5 is a schematic cross-sectional view showing a centrifugal compressor in which the impeller of the present invention is incorporated, which is another example of a product using the HEA member according to the present invention. By using the impeller of the present invention exhibiting excellent durability even under severe stress / corrosion environment, it is possible to contribute to improvement of long-term reliability of the centrifugal compressor.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

[Experiment 1]
(Preparation of HEA powder 1-6)
The raw materials were mixed with the nominal composition shown in Table 1, and the raw material mixing and dissolving step was performed in which the molten metal was formed by melting by a vacuum melting method. Next, the atomization process which forms alloy powder from a molten metal was performed by the gas atomization method. Next, the obtained alloy powder was classified by sieving to select a particle size of 45 to 105 μm to prepare HEA powders 1 to 6. When the particle size distribution of the HEA powders 1 to 6 was measured using a laser diffraction type particle size distribution measuring apparatus, the average particle size of each was about 70 μm.

[Experiment 2]
(Preparation of HEA members 1e to 6e of an alloy laminate model)
For the HEA powder 1 prepared in Experiment 1, using the powder additive manufacturing equipment (Arcam AB, model: A2X) as shown in Fig. 2, the alloy additive manufacturing using the EBM method is performed according to the procedure of the additive manufacturing process. A body (14 mm diameter x 85 mm high columnar material, height direction is the stacking direction) was modeled. The calcining temperature of the powder bed was 950 ° C.

After the additive manufacturing process, an extraction process of removing the temporary sintered body around the alloy additive manufacturing body by sandblasting using HEA powder 1 was performed, and the HEA member 1e of the alloy additive manufacturing body was taken out.

The HEA powders 2 to 6 were subjected to the additive manufacturing process and the extraction process in the same manner as described above, thereby producing HEA members 2e to 6e of alloy additive manufacturing objects.

[Experiment 3]
(Manufacture of HEA members 1c to 4c of ordinary cast materials)
For the HEA powder 1 prepared in Experiment 1, a normal casting (14 mm wide x 80 mm long x 15 mm high prism) is cast by arc melting using a copper water-cooled mold. A cast material HEA member 1c was produced. In order to suppress elemental segregation and texture spots during casting as much as possible, dissolution was repeated 5 times or more.

For HEA powders 2 to 4, HEA members 2c to 4c of ordinary cast materials were produced in the same manner as the HEA member 1c.

[Experiment 4]
(Microstructure observation of HEA materials)
A specimen for microstructural observation was collected from each HEA member produced above, and microscopic observation was performed using an optical microscope, a scanning electron microscope (SEM), and an X-ray diffraction (XRD) apparatus. Table 2 shows the microstructure observation results together with the production specifications of each HEA member.

As shown in Table 2, the matrix structure of the HEA members 1e to 6e produced by the additive manufacturing method is a structure in which fine columnar crystals (average particle size of 100 μm or less) are forested along the stacking direction of the alloy additive manufacturing body. (So-called rapidly solidified structure). The crystal structure of the columnar crystals was basically simple cubic (SC). As a result of XRD measurement, when it is difficult to distinguish between SC and face-centered cubic (FCC) (when it is difficult to determine that it is not FCC), “SC (FCC)” Indicated.

On the other hand, the matrix structure of the HEA members 1c to 4c produced by the ordinary casting method had a structure composed of equiaxed crystals having an average particle diameter of more than 100 μm. The crystal structure of the columnar crystal clearly contained FCC.

From the observation results of these matrix structures, it can be said that “whether the matrix structure consists of columnar crystals or equiaxed crystals” and “whether the crystal structure of the matrix phase clearly contains FCC” indicate the solidification rate of HEA ( In other words, the length of stay in the temperature range where atoms can be rearranged was thought to be strongly affected.

Further, regarding the precipitation of intermetallic compounds, as a result of XRD measurement, it was confirmed that the main precipitation phase was a Ni ₃ Ti phase in all HEA members. From the XRD measurement results, the precipitation of NiTi phase and NiTi ₂ phase could not be denied (in other words, there was a possibility that NiTi phase and NiTi ₂ phase were slightly precipitated).

On the other hand, in the precipitation form of the intermetallic compound, a large difference was observed depending on the method for producing the HEA member. 3A and 3B shown above are electron microscope observation images showing examples of the microstructure of the HEA member 1e. FIG. 6 is an electron microscope observation image showing an example of the microstructure of the HEA member 1c.

As described above, in the HEA members 1e to 6e produced by the additive manufacturing method, the acicular crystals of the main precipitation phase were dispersed and precipitated in a three-dimensional lattice shape. On the other hand, as shown in FIG. 6, in the HEA members 1c to 4c manufactured by the normal casting method, it was observed that the acicular crystals were randomly assembled.

[Experiment 5]
(Measuring mechanical properties and corrosion resistance of HEA materials)
A specimen for a tensile test (parallel part diameter: 4 mm, parallel part length: 20 mm) was collected from each HEA member produced above. The HEA members 1e to 6e produced by the additive manufacturing method were collected so that the longitudinal direction of the test piece coincided with the additive manufacturing direction.

Each specimen was subjected to a room temperature tensile test using a universal material testing machine (based on JIS Z 2241, strain rate: 5 × 10 ⁻⁵ s ⁻¹ ), and the tensile strength and elongation at break were measured. The measurement result of the tensile test was obtained as an average value of 8 measurements excluding the maximum value and the minimum value of 10 measurements. In the evaluation of tensile strength, 1000 MPa or more was judged as “pass”, and less than 1000 MPa was judged as “fail”. In addition, the evaluation of elongation at break was 3% or more as “pass” and less than 3% as “fail”. The results are shown in Table 3 below.

In addition, a polarization test piece (15 mm long × 15 mm wide × 2 mm thick) for pitting corrosion test was collected from each HEA member produced above. The pitting corrosion test was performed on each polarization test piece in accordance with JIS G 0577. Specifically, “Test area: 1 cm ² , crevice corrosion prevention electrode is attached to polarization test piece, reference electrode: saturated silver chloride electrode, test solution: 3.5% sodium chloride aqueous solution degassed with argon gas, test temperature: The anodic polarization curve of the polarization test piece was measured under the conditions of “30 ° C., potential sweep rate: 20 mV / min”, and the pitting corrosion occurrence potential corresponding to the current density of 100 μA / cm ² was obtained. In the evaluation of the pitting corrosion occurrence potential, 1.0 V or more was determined as “pass”, and less than 1.0 V was determined as “fail”. The results of the pitting corrosion test are also shown in Table 3.

As shown in Table 3, the HEA members 1e to 3e, 5e, and 6e produced by the additive manufacturing method as an example of the present invention exhibit a tensile strength of 1000 MPa or more and a breaking elongation of 3% or more, which are good. It has been demonstrated that it has excellent mechanical properties. Further, it was confirmed that the HEA members 5e and 6e having relatively low contents of the Ni component and the Ti component are particularly excellent in elongation at break.

On the other hand, the HEA members 1c to 4c and the HEA member 4e whose alloy composition does not fall within the scope of the present invention, which are comparative casting examples, have a tensile strength of less than 1000 MPa and / or an elongation at break of less than 3%. The overall mechanical properties were unacceptable. In addition, the HEA member 4e was rejected in spite of being manufactured by the additive manufacturing method, so that it was confirmed that addition of Mo exceeding 8 atomic% was not preferable.

On the other hand, regarding corrosion resistance, all HEA members showed a pitting corrosion occurrence potential of 1.0 以上 V vs. Ag / AgCl or higher, and it was confirmed that they have excellent corrosion resistance regardless of the manufacturing method and microstructure. In other words, the HEA member of the present invention is considered to have excellent corrosion resistance due to the combination of elements itself (Co—Cr—Fe—Ni—Ti—Mo).

[Experiment 6]
(Production and inspection of products using HEA materials)
The impeller shown in FIG. 4 was manufactured in the same manner as the method for manufacturing the HEA member 1e (by layered manufacturing using the HEA powder 1). The obtained impeller was subjected to internal defect inspection by X-ray CT scan and dimension measurement. As a result, no special internal defects were observed, and no deformation with respect to the design dimensions was observed. From this experiment, the effectiveness of the present invention was confirmed.

The above-described embodiments and examples are described for the purpose of helping understanding of the present invention, and the present invention is not limited to the specific configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. That is, according to the present invention, a part of the configurations of the embodiments and examples of the present specification can be deleted, replaced with other configurations, and added with other configurations.

10 ... molten metal, 20 ... alloy powder, 100 ... EBM powder additive manufacturing equipment, 110 ... electron beam control unit, 120 ... powder control unit, 111 ... tungsten filament, 112 ... anode, 113 ... electron beam, 114 ... astigmatism Correction device, 115 ... focus coil, 116 ... deflection coil, 121 ... stage, 122 ... base plate, 123 ... powder hopper, 124 ... rake arm, 210 ... powder bed, 220 ... solidified layer, 230 ... alloy laminate model.

Claims (12)

An alloy member made of a high-entropy alloy,
Chemistry containing each element of Co, Cr, Fe, Ni, and Ti in the range of 5 atomic% to 35 atomic%, Mo in the range of more than 0 atomic% to 8 atomic%, with the balance being inevitable impurities Having a composition,
The alloy member is a high entropy alloy member in which an intermetallic compound phase of needle-like crystals is dispersed and precipitated in a mother phase crystal. In the high entropy alloy member according to claim 1,
The high entropy alloy member, wherein the acicular crystals are dispersed and precipitated in a three-dimensional lattice shape. In the high entropy alloy member according to claim 1 or 2,
The chemical composition of the high-entropy alloy is such that the Co is 20 atomic% to 35 atomic%, the Cr is 10 atomic% to 25 atomic%, the Fe is 10 atomic% to 25 atomic%, the Ni A high entropy alloy member characterized by containing 15 at% to 30 at% and Ti at 5 at% to 15 at%. In the high entropy alloy member according to claim 1 or 2,
The high-entropy alloy has a chemical composition of 25 to 33 atomic percent of Co, 15 to 23 atomic percent of Cr, 15 to 23 atomic percent of Fe, Ni A high entropy alloy member comprising: 17 atomic percent to 28 atomic percent, Ti containing 5 atomic percent to 10 atomic percent, and Mo containing 1 atomic percent to 7 atomic percent. In the high entropy alloy member according to claim 1 or 2,
The high-entropy alloy has a chemical composition of 27 to 33 atomic percent of Co, 18 to 23 atomic percent of Cr, 18 to 23 atomic percent of Fe, Ni A high entropy alloy member comprising: 17 atomic percent to 24 atomic percent; Ti containing 5 atomic percent to 8 atomic percent; and Mo containing 1 atomic percent to 3 atomic percent. In the high entropy alloy member according to any one of claims 1 to 5,
The high-entropy alloy member, wherein the intermetallic compound phase includes a Ni ₃ Ti phase. In the high entropy alloy member according to any one of claims 1 to 6,
A high-entropy alloy member having a tensile strength of 1000 MPa or more and a breaking elongation of 3% or more. In the high entropy alloy member according to any one of claims 1 to 7,
The high-entropy alloy member, wherein the parent phase crystal is a columnar crystal and the crystal structure includes a simple cubic crystal. It is a manufacturing method of the high entropy alloy member according to any one of claims 1 to 7,
A raw material mixing and melting step of mixing and melting the raw materials of the alloy to form a molten metal;
An atomizing step of forming alloy powder from the molten metal;
A method of manufacturing a high-entropy alloy member, comprising: an additive manufacturing process for forming an alloy additive manufacturing body having a desired shape by a metal powder additive manufacturing method using the alloy powder. In the manufacturing method of the high entropy alloy member according to claim 9,
The additive manufacturing process includes a powder bed forming process for forming a powder bed of the alloy powder,
A powder bed calcining step of heating the entire powder bed to form a pre-sintered powder bed;
The temporary sintered body is locally heated to form a micro molten pool of the alloy, and the micro molten pool is moved and sequentially solidified while scanning the local heating in the plane of the temporary sintered body. A method for producing a high-entropy alloy member, comprising: a local melting / solidifying layer forming step of forming a solidified layer of an alloy. A product using a high-entropy alloy member,
The high entropy alloy member is the high entropy alloy member according to any one of claims 1 to 8,
A product using a high-entropy alloy member, wherein the product is an impeller of a fluid machine. A centrifugal compressor incorporating the impeller according to claim 11.

Images